Shell-model predictions for 41,42Cl( beta -)41,42Ar and the A=41-43 Ar isotopes.

Abstract

Shell-model calculations in the model space of the (0d,1s) and (0f,1p) major shells are made for the 1/${2}^{+}$ and 3/${2}^{+}$ states of $^{41}\mathrm{Cl}$, the odd-parity states of $^{41}\mathrm{Ar}$, and the even-parity states of $^{42}\mathrm{Ar}$. Calculations for $^{42}\mathrm{Cl}$, the even-parity states of $^{41}\mathrm{Ar}$, and the odd-parity states of $^{43}\mathrm{Ar}$ were performed with various degrees of truncation. The results for the $^{41}\mathrm{Cl}$ ground state indicate ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=3/${2}^{+}$ with a binding energy of -345 183 keV in excellent agreement with the experimental value of -345 020\ifmmode\pm\else\textpm\fi{}150 keV. The predicted binding energies of $^{41\mathrm{\ensuremath{-}}43}\mathrm{Ar}$ are also in good agreement with experiment. The wave functions for the A=41 and 42 nuclei are used to calculate first-forbidden ${\mathrm{\ensuremath{\beta}}}^{\mathrm{\ensuremath{-}}}$-decay rates. The 1/${2}^{+}$ and 3/${2}^{+}$ states of $^{41}\mathrm{Ar}$ are considered in a truncated model space and the results are used to estimate the allowed ${\mathrm{\ensuremath{\beta}}}^{\mathrm{\ensuremath{-}}}$-decays rates of $^{41}\mathrm{Cl}$. Spectroscopic factors and electromagnetic transition rates are calculated for $^{41}\mathrm{Ar}$ and compared to experiment. $^{43}\mathrm{Ar}$ is predicted to have a 5/${2}^{\mathrm{\ensuremath{-}}}$ ground state.